[uml-devel] [RFC PATCH 10/11] SKAS4 - Introduce STUB_ADDR

[Jeff Dike <jdike@addtoit.com>]

There were a number of repetitions of the calculation of an stub
address in a process address space.  This introduces STUB_ADDR to
eliminate the common code.

diff --git a/arch/um/include/skas/skas.h b/arch/um/include/skas/skas.h
index 061a362..331f343 100644
--- a/arch/um/include/skas/skas.h
+++ b/arch/um/include/skas/skas.h
@@ -10,6 +10,9 @@
 
 extern int have_siginfo_segv;
 
+#define STUB_ADDR(x) (STUB_CODE + (unsigned long) (x) - \
+		      (unsigned long) &__syscall_stub_start)
+
 extern int userspace_pid[];
 extern int proc_mm, ptrace_faultinfo, ptrace_ldt;
 extern int skas_needs_stub;
diff --git a/arch/um/os-Linux/skas/mem.c b/arch/um/os-Linux/skas/mem.c
index efda5e1..a737d6d 100644
--- a/arch/um/os-Linux/skas/mem.c
+++ b/arch/um/os-Linux/skas/mem.c
@@ -45,9 +45,7 @@ static int __init init_syscall_regs(void)
 	get_safe_registers(syscall_regs);
 	stub_entry = &batch_syscall_stub;
 
-	syscall_regs[REGS_IP_INDEX] = STUB_CODE +
-		((unsigned long) stub_entry -
-		 (unsigned long) &__syscall_stub_start);
+	syscall_regs[REGS_IP_INDEX] = STUB_ADDR(stub_entry);
 	return 0;
 }
 
diff --git a/arch/um/os-Linux/skas/process.c b/arch/um/os-Linux/skas/process.c
index 522d0f1..fc92a5d 100644
--- a/arch/um/os-Linux/skas/process.c
+++ b/arch/um/os-Linux/skas/process.c
@@ -229,10 +229,7 @@ static int userspace_tramp(void *stack)
 	}
 	if (!ptrace_faultinfo && (stack != NULL)) {
 		struct sigaction sa;
-
-		unsigned long v = STUB_CODE +
-				  (unsigned long) stub_segv_handler -
-				  (unsigned long) &__syscall_stub_start;
+		unsigned long v = STUB_ADDR(stub_segv_handler);
 
 		set_sigstack((void *) STUB_DATA, UM_KERN_PAGE_SIZE);
 		sigemptyset(&sa.sa_mask);
@@ -400,9 +397,7 @@ static int __init init_thread_regs(void)
 {
 	get_safe_registers(thread_regs);
 	/* Set parent's instruction pointer to start of clone-stub */
-	thread_regs[REGS_IP_INDEX] = STUB_CODE +
-				(unsigned long) stub_clone_handler -
-				(unsigned long) &__syscall_stub_start;
+	thread_regs[REGS_IP_INDEX] = STUB_ADDR(stub_clone_handler);
 	thread_regs[REGS_SP_INDEX] = STUB_DATA + UM_KERN_PAGE_SIZE -
 		sizeof(void *);
 #ifdef __SIGNAL_FRAMESIZE

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